(a) Field of the Invention
The present invention relates to a thin film transistor array substrate. More particularly, the present invention relates to a thin film transistor array substrate, a method for manufacturing the same and a system for inspecting the substrate.
(b) Description of the Related Art
Liquid crystal displays are at present the most commonly used flat panel display. The liquid crystal display (LCD) is structured having liquid crystal material injected between two substrates. Voltages of different potentials are applied to electrodes of the substrates to form electric fields such that the alignment of liquid crystal molecules of the liquid crystal material is varied. Accordingly, the transmittance of incident light is controlled to enable the display of images.
Formed on one of the substrates is wiring, which transmits image signals and scanning signals. The wiring defines pixels in a matrix arrangement, and each pixel is electrically connected to the wiring. Formed on the same substrate as the wiring are thin film transistors (TFTs) for discontinuing the transmittance of the image signals, and pixel electrodes for transmitting the image signals. This substrate is referred to as a TFT substrate.
Pads are connected to ends of the wiring. The pads are used as a means to transmit the scanning signals and image signals to the wiring from an external drive circuit. To prevent damage to the pads, it is preferable to cover the pads with auxiliary pads made of a conducting material in another layer.
However, a space between the pads decreases as the resolution of the LCD increases. Thus, contact defect of a probe pin used in inspecting the liquid crystal panel increases contact resistance of the pads. This is particularly true when IZO (indium zinc oxide), which has a high surface contact resistance, is used for the auxiliary pads, making it unable to inspect the liquid crystal panel.